1. Field of Invention
This invention relates to multielectrode sensors and electronic systems and software for multielectrode sensors and other electrochemical multielectrode devices.
2. Background
Multielectrode array sensors (see U.S. Pat. Nos. 6,683,463 and No 6,132,593) have been used for corrosion monitoring and electrochemical studies [L. Yang and N. Sridhar, “Coupled Multielectrode Online Corrosion Sensor”, Materials Performance, 2003, September issue, page 48]. U.S. Pat. No. 6,683,463, to Yang and Sridhar (2004), disclosed a coupled multielectrode sensor system in which each electrode is connected to a common joint through a resistor, and a multichannel high-precision voltmeter is used to scan the potential drop across each resistor to obtain the current flowing though the resistor. However, the use of a single resistor for each electrode of the sensor limits the range of corrosion rates in which the sensor effectively simulates the one-piece-metal behavior because the one-piece-metal concept requires that the potentials of all the electrodes of the sensor are essentially the same. In addition, no current software allows the flexible configuration of the multiple electrodes during the measurements. This invention is related to several electronic systems and sensor designs, and a user-friendly software program for monitoring corrosion or studying electrochemical processes using the concept of multielectrode sensors or electrochemical devices.
The inventor has recently filed a patent application related to the instrument and user-friendly software, titled “An Electronic System and Software for Multielectrode Sensors and Electrochemical Devices.” In that patent application, a basic electronic unit, an integrated electronic system, and the associated software program for coupled multielectrode electrochemical devices or sensors were disclosed. The basic electronic unit uses different values of resistors for coupling the multiple electrodes in a sensor, so that the effective value of the coupling resistance can be dynamically changed according to the magnitude of the measured coupling current during the measurement. This feature allows the electronic unit to measure a wide range of coupling currents, without compromising the principle that the coupled electrochemical device simulates the one-piece-metal behavior. The integrated electronic system uses several basic electronic units, so that it can simultaneously measure several independent multielectrode electrochemical devices or sensors that have a small number of electrodes, or measure one or more multielectrode devices or sensors that have a large number of electrodes. The software gives users the ability to change the data acquisition parameters dynamically during the measurements.
The present patent application is an improvement of the previously filed patent application. Some of the improved features by the present invention include:                An electronic system that has a large electrode connected to the coupling joint through a resistor element, to adjust the potential of the electrodes.        An electronic system and software program that automatically change the values of the coupling resistors, so that the potentials of a group of electrodes or the entire electrodes of a sensor are similar, or automatically disconnect malfunctioning electrodes from the coupling joints to avoid the effect by such electrodes.        An electronic system that uses an ammeter or a zero-resistance-ammeter to measure the coupling currents and has resistors between the electrodes and the coupling joint, to reduce the transient current produced during switching.        A software program that also keeps track of the cumulative charge for each electrode of the multielectrode device, so that the cumulative corrosion depth or electrodeposition thickness can be calculated based on the cumulative charge from each electrode.        A multielectrode sensor system with a dual-sensor design that allows it to be used in systems containing electrochemically active species.        
REFERENCE NUMBERS OF DRAWINGS 5basic electronic unit 5abasic electronic unit for working sensor 5bbasic electronic unit for baseline sensor 6voltage-measuring unit 10electrode wires from a basic electronic unit for connection to thefirst through the last electrodes of a multielectrode device or agroup of electrodes of a multielectrode device 12coupling joint of a basic electronic unit 14large electrode 20group of auto switches that are connected to each electrodein parallel (called K switches) 22K switches (filled symbols indicate closed state and opensymbols indicate open state) 30group of auto switches connecting each electrode to a voltmeteror an ammeter (called K″ switches) 32K″ switches (filled symbols indicate closed state, and opensymbols indicate open state) 40auto switch connecting the coupling joint to the voltmeter (calledK′ switch; filled symbols indicate closed state, and open symbolsindicate open state) 50group of resistors that are between each electrode and the couplingjoint (R group resistors) 51R resistor #1 (R1) with the lowest resistance value 52R resistor #2 (R2) with a higher resistance value 53R resistor #j (Rj) with the highest resistance value 60a group of resistors in the voltage-measuring unit that are inparallel with the R group resistors (called R′ group resistors) 61R′ resistor #1 (R′1) with the lowest resistance value 62R′ resistor #2 (R′2) with a higher resistance value 63R′ resistor #j (R′j) with the highest resistance value 70group of auto switches that close or open the R′ resistors(called K″″ switches) 72K″″ switches (filled symbols indicate closed state, and opensymbols indicate open state) 74voltmeter 76ammeter or zero-resistance ammeter 80auto switches that connect between the coupling joints of anytwo or more basic electronic units (called K″′ switches) 81switch for measurement of the potential of the coupling jointagainst a reference electrode with the voltmeter (called K7 switch) 82reference electrode 83cathode 84power source 85group of resistors that are between the coupling joint and thecathode (R″1<R″2< . . . <R″p) 86auto switches that close or open the R″ resistors (they are calledK5 switches here; filled symbols indicate closed state, and opensymbols indicate open state) 87switch that connects the reference electrode to the input of thevoltmeter (called K6 switch) 88switch that connects the wire from the K″ switch to a voltmeter(called K9 switch) 89switch that connects the wire from the K″ switch to an ammeter(called K8 switch) 90instrument panel 91electrical connector for basic electronic unit (designated BankA, B, C, . . . for 1st, 2nd, 3rd, . . . basic electronic units) 92electrical connector for two or more basic electronic units(with more pins) 93electrical connector for more basic electronic units(with even more pins) 94numerical number showing the number of pins used on connectoror available for measurement. 96connector connected to the coupling joint of a basic electronic unit(designated as A, B, C, . . . for 1st, 2nd, 3rd, . . . basicelectronic units)102cables that connects a group of wires from each basic electronicunit to the different types of electrical connectors110working sensor in a dual sensor design112baseline sensor in a dual sensor design120combination sensor in a dual sensor design122working sensor electrode in a combination sensor124baseline sensor electrode in a combination sensor126cable connected to working sensor electrodes of a combinationsensor128cable connected to baseline sensor electrodes of a combinationsensor130sensor body or sensor protection tube132sensing electrodes134insulation135electrical cable140large removable rod-shaped electrode with a female thread atone end142metal connector with a male thread at end forconnection to the large removable rod-shaped electrode144large removable tube-shaped electrode with internal thread146external thread on sensor body for attachinglarge removable tube-shaped electrode and for formingelectrical contact between the embedded wire and the electrode148embedded wire for connection to the tube-shaped large removableelectrode if body is made of non-conducting material